This document discusses the advancement of air purifiers. It begins by outlining the problem of increasing air pollution in many cities due to factors like population growth and industrialization. The objective is to purify indoor air economically for public health. The designed air purifier uses multiple filter types in sequence, including a pre-filter, cold catalyst, carbon filter, antibacterial filter, HEPA filter, and UV light, to remove particulate matter, odors, and toxic gases. Experimental results found the designed purifier achieved over 90% removal efficiency for various air pollutants tested. The document concludes the purifier could be made affordable at large production volumes.

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ADVANCEMENT IN AIR PURIFIER
Neelakantha V Londe1, Pavan Kumar J2, Abhishek S Patil3, Srinidhi N4
1234Department of Mechanical Engineering
Mangalore Institute of Technology & Engineering, Moodbidri
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Abstract -Rapid industrialization and exponential
growth of population directly or indirectly resulted in air
pollution in different ways. Just like the need of fresh and
pure water for healthy human habitat, fresh air is also
another very important need of life. At present in most of
the cities across the world, the air pollution is increasing
and is at alarming state. The objective of this project is to
filter and purify the surrounding air at an economical way
for healthy life of population. Even though many varieties
of air filters are available in the market, they are both built
with limited air filters and costlier too. The present work
uses number of types of air filters to remove macro and
micro particulate matter, odor, toxic gases etc. from the
incoming air to the filter. The purification of air in a room is
continuously done and made to circulate. The purified air
can also be connected to air conditioner at its inlet to
reduce load on it. The device makes use of pre filter and
cold catalyst, carbon filter, anti-bacterial filter, Ultraviolet
light in sequence for filtering the incoming air. It is
experimentally proved that the designed filter has higher
air filtering efficiency and cost of the device may be made
affordable if manufactured in large volume.
Key Words: Air pollution, Air purification, Cold
catalyst, HEPA Filter, Air Quality
1. INTRODUCTION
The common problem during the summer season is the
air pollution by smoke, dust and allergies. Higher air
quality index (AQI) indicates increased air pollution
which leads to higher health risks. Due to increase in air
pollution, people frequently use air purifier as a basic
need of life for domestic use or in offices in metropolitan
cities as precautionary measure of issues due to polluted
air. Lower AQI below 50 is said to be safe whereas higher
AQI above 300 level pose severe impacts on health due to
polluted air. The five major air contaminants are ground
level ozone, particulate matter PM2.5 to PM10, Carbon
monoxide, Sulphur Dioxide, Nitrogen Dioxide.
The contaminants like dust particles, fine fibers
present in the air are filtered and removed by air
purifiers. Commercially available air purifiers may be
small units or larger units. These can be fixed to an air
handler unit (AHU) or to a heating and air-conditioning
(HVAC) unit. Air purifiers are also used to remove
impurities such as carbon dioxide gas from air before
processing. The contaminants from air are removed
using different filters in different stages.
Air purifier with HEPA filter, Activated Carbon Filter
(ACF) enhances AQI of filtered air. Particulates of relatively
larger and smaller size are filtered at various stages. Solar
energy operated air filters are also developed Baltrėnas, P.
Zagorskis, etal analyzed proposed negative ionic air
purifiers. They did the test in natural decay & air mixing
mechanism in a sealed chamber. It is studied that, at a
minimum height of 60 cm, filtering efficiency is maximum.
Subramanian Sundar Rajan[2] evaluated in his research
papers that, HEPA and activated carbon filters are effective
to remove dirt molecules. HEPA filters have an efficiency of
up to 99.97% to filter micro particles and disinfect
microorganisms present in air [3]. Sulphur and its
constituents are filtered by activated carbon which are in
clusters of sulfates and sulfites, having bonded to Na and
Fe. The adsorption efficiency depends on time. Research
has shown that carbon filter can absorb Slphur,Sodium
&Iron Sulphites. [4]. S. B. Divate, S. R.Kadam et al [5] shown
that activated carbon has higher adsorbing efficiency than
other filters. Yoshiko Yoda, Kenji Tamura et al [6] have said
that it is not clear still whether air purifiers increase
respiratory health. Their research included thirty two
healthy individuals and two air purifiers and tested for 12
weeks. Study conducted in Shanghai, showed a significant
57% drop in PM2.5. When the room was kept sealed for
two days.. A study on COPD patients exhibited that exhale
of hydrogen sulfide & nitric oxide increased significantly
with the increase in air pollutants. FeH2S is efficient in
detection of the adversative respiratory issues due to air
pollution.
2. MATERIALS & METHODOLOGY:
Advanced air purifiers have various stages of air filtration;
cold Catalyst filter Honeycomb activated carbon filter,
Antibacterial filter, HEPA Filter, Ultraviolet sterilize light
filter. Pre-Filter filter removes heavy particulates, human
hair etc. The cold catalyst filter removes benzene
ammonia, formaldehyde hydrogen sulphide and harmful
gases. Through adsorption process Activated Carbon Filter
(ACF) removes contaminants from air. It also removes
odors from air. Addition of activated carbon, zeolite,
potassium permanganate to air to the filtering system
absorb odour, smoke, chemical vapors and other gases
present in contaminated air. Filtering system with

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chemical adsorption materials or activated carbon
neutralizes odour and harmful chemicals and gases in its
pores
2.1 Pre-Filter
The macro sized particulates which are usually more in
polluted air, are trapped initially using a pre-filter. This is
also necessary to safe guard the delicate HEPA in the next
stage of filtering. Otherwise the macro sized particulates
will block the filters arranged in the next levels of filtering.
2.2 HEPA Filter
A fine fiber like material used in making HEPA filter & is
folded back& forth to form a maze of randomly
arranged fibers. This offers a very large surface for air
to get forced in by the purifier fan. Suitable design is
made for smooth air flow through the system during air
filtration. Allowing relatively large air flow filters the
pollutants effectively. Usually HEPA filters last long for
about three to four years.
2.3 Ultraviolet Light
A variety of bacteria’s will be sterilized using ultraviolet
light. UV light works independently to neutralize
microorganisms. Use of germicidal lamp purifies the air.
2.4 Suction Fan
To pull the air through the filter, a small electric fan as is
used on one side of filter system where as the filtered air
will exit on the other side of fan. Fan is an important
component in filter system.
2.5 Cold catalyst filter
The cold catalyst filter is effective at removing
formaldehyde, benzene ammonia, hydrogen sulphide, and
harmful gases.
2.6 Carbon Filter
Absorbs and collects dust, pet hair, allergens, smoke
fumes and harmful gases. Activated Carbon Filter uses
activated carbon to remove contaminants from air
through adsorption. In addition to pollutants this filter is
also effective in removing odours from the air.
2.7 Anti-microbial Filter
Anti-microbial Filter is just 5 microns thick helps to trap
harmful, disease causing microbes and keep them out of
the air that you breathe indoors. Antimicrobial agent
effectively kills bacteria in air
3 FILTERING PROCESS
When the fan operates, a suction action is formed across
the filters and air starts moving towards lower pressure
region. The cold catalyst filters initially filters the harmful
gases are. The macro particulates get arrested in the
pores of activated carbon filter. Afterwards, the air passes
through the antimicrobial filter. The air is forced to pass
through an antimicrobial agent polypropylene
membrane. The microorganisms get trapped and
prevented from scattering. The unfiltered micro and
macro particulates still present in the air get captured in
HEPA Filter. The micro particles and microorganisms like
bacteria; fungus etc. up to a level of 0.03 microns will be
filtered. With an efficiency of about 90 %. The UV light
kills the microorganisms that pass through.
Table -1: Analysis of purification efficiency
*TVOC-Total Volatile Organic Compound
Air sample is tested for quality of air filtering through
the designed system. Initially the environment air from a
room is tested for its air quality. The readings are taken
in a testing machine. Afterwards the environment air
made of same room is passed as input air to the air filter
device. The readings are taken again from testing
machine. The difference of initial and later readings is
taken and compared as shown in following Table No.
1.Chart 1 shows the experimental analysis of
purification efficiency.
COMPARISON OF AIR QUALITY TESTED BEFORE AIR
FILTERING & AFTER AIR FILTERING
Before
filtering
After
filtering
%
Purification
CO 200 20 90
NOX 190 14 92.6
TVOC 146 16 89.04
Particulate
matter in
ppm
130 13 90

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Chart -1: Analysis of air purifier efficiency
Fig -1: Air purifier system
4. CALCULATION
4.1 Clean Area Delivery Rate (CADR)
Clean Air Delivery Rate (CADR) is measured as cubic
meter (m3) of air filtered per hour or cubic foot (ft3) of air
per minute. In other words it indicates rate of air
Purification in volume per unit time. Higher purification
rate means higher CADR value which is good. It is
suggested to have CADR number as 3 by Association of
Home Appliance Manufacturers
(AHAM) for pollen, dust, smoke and tobacco removal on
an air purifier.
CADR value = Square Feet of Room / 1.55
Area of Room = 275 sq.ft.
CADR value = 275 / 1.55 = 161.29 m3/hr.
4.2 Air Change per Hour (ACH)
ACH means how many times the complete volume of air
inside a room repeatedly gets filtered per hour. If the
purifier filters the air in the room three times an hour.
4.3The ACH index reflects the effectiveness of the air
purifier.
CADR = 161.29 m3/hr.
CADR = 300 x 0.588 = 104.19 ft3 / minute
Air changed in an hour = 104.19 x 60 = 6251.4 (CADR in
CFM x number of minutes in an hour)
Room volume= 2475 (275 x 9), as Room height is assumed
to be 9 ft.
ACH rating = Air changed in an hour / Room Volume
ACH rating = 6251.4 / 2475 = 2.56
5. MERITS & FUTURE SCOPE
i] The designed air filter is highly efficient and removes
fine size particulates of micron size.
ii] Even the continuous usage of HEPA filter will not allow
accumulated pollutants from filter
iii] The designed filter does not produce harmful gases
during filtering.
iv] As it removes all types of solid and gaseous pollutants,
it is highly useful in hospitals, operation theaters, and
indoor houses where it is required to maintain high
standard of air quality index.
v]In general the air condition systems does not remove
chemicals in gaseous state, or odor from air effectively but
if we incorporate the air filtering system with air
conditioner, the output air will become highly purified..
The air conditioner the filtered air can be sent to air
conditioner so that the load on the air-conditioner will be
reduced. In other words, output of this filter may be
connected to input duct of air conditioner for effective air
conditioning.
6. CONCLUSIONS
Air purifiers developed on various technologies are
available in the market. Advanced air purifiers use
combination of technologies to enhance air purification.
The HEPA types of filters remove viruses from air during
purification. Some versions also remove the micro dust
particles as well pollen contents from air. HEPA filters
manufactured under set standards may have highest
0
50
100
150
200
250
CO NOX TVOC Particulate
matter in ppm
Analysis chart
Before filtering After filtering % Reduction

4. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 09 Issue: 06 | June 2022 www.irjet.net p-ISSN: 2395-0072
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efficiency around 90 %. They filter even 0.03-micron size
particulates from air. The analysis of air quality after
filtration indicates that the designed combination of
different air filters results in good air quality index of
purified air.
Acknowledgement: we are thank of the Dept of
Mechanical Engineering, MITE, Moodabidri for the support
given.
REFERENCES
[1] A. Shiue, S. C. Hu, and M. L. Tu, “Particles removal by
negative ionic air purifier in cleanroom, Aerosol Air Qual.
Res., vol. 11, no. 2, pp. 179–186, 2011, doi:
10.4209/aaqr.2010.06.0048.
[2] S. Sundarrajan, K. L. Tan, S. H. Lim, and S. Ramakrishna,
“Electro spun nano fibers for air filtration applications,”
Procedia Eng., vol. 75, pp. 159–163, 2014, doi:
10.1016/j.proeng.2013.11.034.
[3] A. R. K. B and A. Ms, “Self-Sustainable Air Purifier with
Air Cooling System,” vol. 7, no. 10, pp. 1–4, 2019.
[4] S. Ge, Z. Liu, Y. Furuta, and W. Peng, “Characteristics of
activated carbon remove sulfur particles against smog,”
Saudi J. Biol. Sci., vol. 24, no. 6, pp. 1370–1374, 2017, doi:
10.1016/j.sjbs.2016.12.016.2014
5] S. B. Divate and R. V Hinge, “Review on Research
Removal of Phenol from Wastewater by Using Different
Methods,” Int. J. Sci. Res. Publ., vol. 4, no. 1, pp. 2250–3153,
2014
[6] Y. Yoda, K. Tamura, S. Adachi, N. Otani, S. F. Nakayama,
and M. Shima, “Effects of the use of air purifier on indoor
7] Wu S, Wang B, Yang D, Wei H, Li H, Pan L, Huang J, Wang
X, Qin Y, Zheng C, Shima M, Deng F, Guo X. Ambient
particulate air pollution and circulating antioxidant
enzymes: A repeated-measure study in healthy adults in
Beijing, China.
[8] Kim, S. M., Choi, Y., & Suh, J. (2020). Applications of the
open-source hardware Arduino platform in the mining
industry: A review. Applied Sciences (Switzerland), 10(14)
[9] Kim, Y.J., Maeng, K.H. and Lee, S.K., Koninklijke Philips
NV,2016.Air purifier. U.S. Patent Application29/503,173..
[10] Tsai, P. and Malkan, S.R., University of Tennessee
Research Foundation, 2002. 8HEPA filter. U.S.Patent
6,428,61
[11] Ao, C.H. and Lee, S.C., 2005. Indoor air purification by
photo catalyst TiO2 immobilized on activated carbon filter
installed in an air cleaner. Chemical engineering science,
60(1),pp.103-109
[12] Ciambelli, P., Corbo, P., Palma, V., Russo, P., Vaccaro, S.
and Vaglieco, B., 2001.Study of catalytic filters for soot
particulate removal from exhaust gases. Topics in
Catalysis, 16(1-4),pp.279-284.
[13] Klun, T.P., Dunshee, W.K., Schaffer, K.R., Andrews, J.F.,
Neu, D.M. and Scholz, M.T., 3M Innovative
Properties Co, 2004.Hydrophilic polypropylene fibers
having antimicrobial activity.U.S.Patent6,762,339.
[14] Verdenelli, M.C., Cecchini, C., Orpianesi, C., Dadea,
G.M. and Cresci, A., 2003.Efficacy of antimicrobial filter
treatments on microbial colonization of air panel filters.
Journal of Applied Microbiology, 94(1),pp.9-15
[15] Giokas, D.L., Salvador, A. and Chisvert, A., 2007. UV
filters: from sunscreens to human body and the
environment. TrACTrends in Analytical Chemistry, 26(5),
pp.360-374.Adams, P.C., Tau Systems, 1981.Air purifier and
ionizer. U.S. Patent 4,253,852